Age hardenable nickel alloys



Patented July 18 1950 :umreo [STATE s PATENT oFFlcE AGE 'HARDENABLE f-NIQKEL ALLOYS Clarence George Bieber and Mortimer Pierce Buck, Huntington, W. Va., assig-nors .to The International Nickel Company, Inc

. New .York,

N. Y., a corporation of Delaware No Drawing. ApplicationJanuary 11s, 19.41, Serial Na a/4.20s

5 Claims.

The present :invention relates to nickel alloys, and, more particularly, to hardenable nickel alloys possessing an optimum combination of hot :malleabil-ity and response to :heat treatment.

11; was knownthat nickel .allo-ys could be rendered .hardenableby incorporating in the alloys such amounts of analloying element exhibiting increasing solubility with rise in temperature thatyat :elevated temperatures the solid alloy dissolved a greater amountof the alloying .element than it could retain in stable equilibrium :at lower temperatures. The hardening treatmerit-comprised heating such an alloyto a sufli- .scien'tly elevated temperature to cause at least .part of the hardening element to go into solid solution, {rapidly cooling the alloy to produce a super-saturated solution of the element in the alloy, and then reheating at a lower'temperature to harden the same. Some of these alloys possessed-the ability to harden "to relatively high hardness by proper heat treatment, but .inthese alloys the temperature range of hot malleability was so narrow that, from the point ofry'iew of commercial production, they were practically unworkable. These alloys also were sluggish to cast and almost unmachinable.

When the attempt "was made to broaden the temperature range of amount of at least two ity in the commercial hardening elements .se- .lected from the group consisting or aluminum, titanimnand silicon. V

A .further object of the present invention is the production of nickel alloys having maxim-um hardnessin the aged condition -.comniensurate with satisfactory .forgeability, and good machinring properties.

H ing combinationsof the hardening elements considerable extent, carbon.

hot malleabil-ity by modifying the composition of the-alloy, it was found that the hardenability was greatly lreduced when the temperature range of hot mallleability was broadened sufficiently to make the alloy 'commercially hot malleable. Similarly, :the hardness was reduced if the composition of the hardenable alloys was modified to' obtain good madhinability. The art was faced with the outstanding problem of providing pnickel 1 alloys exhibiting hot malleability over a wide enough temperature range for commercial production, having high hardness in the hardening condition, andgyet being reasonably soft and machina'ble fill the annealed condition,

We have .discovered that nickel alloys characterized by an advantageous combination of :hotmalleability, relative softness in the annealed condition, and high hardness in the heat treated rcondition \can .be :regularly produced on a com- .mericalscale by-the :use of at least two; elements from the group :consisting "of aluminum, titanium aandcsiliconin azcritical ratio to the nickel content.

It isran object :of the present invention to produce hot malleableznic'kel alloys capable of being hardened :by heat treatment to any selected h'azzdness OVEI :a broad hardness range.

:It isranother objectof thezinvention to produce uhardenable nickel alloys containing a critical templated by the present invention are, to a conimproved by the presence of The improvement in the mechanical proper-ties attributable to the presence of carbon may be seen from the illustrative but nonlimiting examples given in Table I which show the beneficial effect of ;carbon in amounts less {than about 0.6% on the response to heat treat- 'ment of liighnickelalloys embodying the present .fIlhe sbeneficial :efiect of carbon illustrated on cAlloysNo. 2to -4.-inclusive, :isssurprising in view .of the known detrimerital-elfectwf (carbon .on nickel alloys containing it'itanium. .as substantiall-y the :OnIyJhardening element. The differ -ence sin the veffect Iof lcarbonlon rthe hardenability 10f alloys embody'mg 'sthe ipresen't invention containing aluminum with titanium as compared with prior :alloys containing titanium as substantially the :only hardening element is well illus- 1 j tially carbon-free.

trated by the alloys whose compositions are given in Table IA.

Table IA Composition Alloy No. Ni Cu Al Ti BaL 30 0 2. 93 53 Bal... 30 .20 2. 93 .53 Bal. 30 0 3. 63

The presence of 0.20%

in the heat treated condition about 60 Brinell 1 numbers above that of Alloy No. 9 which had substantially the same composition as Alloy' No. 10 except that it was substantially carbon-free, whereas the same amount of carbon in Alloy No. 12 made it practically non-hardenable by heat treatment and lowered the hardness in the heat treated condition almost 150 Brinell numbers below Alloy No. 11 which had'the same composition as Alloy No. 12 except that it was substan- The comparatively treatment of alloy 12 is believed to be due to the formation of an inert titanium carbide which decreases the hardening efliciency of the titanium or destroys its hardening ability. The fact that the presence of carbon up to about 0.3% increases the mechanical properties of the material containing both aluminum and titanium made in accordance with the present invention is believed to indicate that the inert titanium carbide does not form in an appreciable amount when aluminum is present with titanium, provided carbon is less than about 0.5% and preferably does not.

exceed about 0.35%. Carbon within the range of about 0.03% to about 0.3% is highly beneficial in alloys embodying the present invention and slight response to heat carbon in Alloy No.10-improved the hardenability and raised the hardness lower the ductility somewhat. For free machining nickel base alloys the carbon content preferably is about 0.2% to 0.3%.

The relative amounts of aluminum, silicon and titanium may vary over a range of several per- ,cent provided the ratio--of-v the nickel to the hardener content is maintained within the limits may be used in amounts up to about 8%, preferably not over 5% of either, while titanium should be less than 11% and preferably is employed in amounts less than 2%. From about 0.25% to under 1% the titanium exerts'its greatest effect in combination with aluminum and/or silicon.

' We have discovered that within the preferred titanium range the optimum combination of. hot malleability, hardenability and. high' hardness in the heat treated condition is obtained when the ratio of the nickel to the weighted hardener content as obtained from the formula. 1

Weighted hardener content=Al+2.3Ti+Si is approximately 15, preferably within the range of 13 to 17, and always within the range of 11 to 20. Since the ratio is a quotient, it is immaterial what unit of weight is used to express the content of nickel, aluminum, titanium and silicon. Thus, for example, the amounts of'these ingredients in any given alloy may be .given' in parts by weight, percentage by weight, etc}. without changing the ratio. Examples of alloys illustrating the beneficial results obtained inhig'h nickel alloys embodying the present invention are giveninTable II: A r

Table II Composition BrinellHardness ea er en N1 Al Ti S1 Others Annealed Treated Increase I 1 WHO=weighted hardener content.

which contain aluminum and/or silicon with titanium. This entirely difierent effect of carbon may be taken to signify that alloys embodying "thepresent novel combination and containing titanium together with one orboth of the ele- 'ments aluminum and silicon differ in kind from prior alloys substantially free of aluminum and silicon, or containing vonly1inefiective. amounts thereof.v For general applications it is havecarbon present in amounts from about preferred 0.15% to 0.20%, although even higher amounts may be'present. If the carbon exceeds about 0.2% precipitation of graphitic carbon may ocour. The presence of 'graphitic carbon greatly improves the machinability of the-alloy and is desirable where free machining properties are required, althoughprecipitated carbon tendsto the group aluminum, titanium and SiliCOIlw Copper also lowers the melting'temperature, thereby narrowing the hot. malleable range; Chromium has an efiectsimilar tov copper, except :t-hatthe base: hardnessuis increased more rapidly. Chromium also increases the recrystallization temperature and the. strength and hardness at elevated temperatures. This increase in strength at nickel.- alloys is substantially overcome by using combinations of at least two metals fromithe .group' aluminum, titanium and silicon. "At'the same time the new alloy possess other desirable properties, including relative softness in the annealed condition, high hardness in the heat treated condition, etc. Certain subject matter originally disclosed in the present application has been described in the following divisional applications, all of which were filed on June 7, 1 9.4 1: Serial No. 397,080 relating to age hardenable nickel-copper alloys; Serial No. 397,081 relating to age hardenable nickel alloys (now abandoned in favor of application Serial No. 477,144 filed February 25, 1943, also now abandoned in favor of the present application); and Serial No. 397,082 relating to age hardenable nickel-chromium alloys (now abandoned in favor of application Serial No. 477,142 filed February 25, 1943 as a continuation-in-part of the present application) The alloys of the present invention can be heat treated in the same manner as prior age hardenable alloys, e. g., in accordance with the technique developed by Mudge and described in U. S. Patents Nos. 1,755,554 to 1,755,557 inclusive, or in accordance with the process of our prior copending application Serial No. 253,350 (now Patent No. 2,234,955) of which the present application is a continuation-in-part. The alloys can be softened by quenching or rapidly cooling from about 1500 F. In the softened condition the alloys can be subjected to mechanical working and cold deformation, and in this condition the alloys lend themselves readily to forming and machining operations. Where hardnesses higher than those obtainable by precipitation hardening of hot worked material are desired, the material may be cold worked either before or after the age hardening treatment. For example, fine spring wires may be cold drawn after the hardening heat treatment since this procedure develops the higher physical properties obtainable in the material. It also produces finished material with a higher luster than can be developed in material which is heat treated after cold drawing. Finish machining may also be carried out after heat treatment to eliminate any discoloration and warping which occur during the heat treatment. Heat treated material may be subjected to subsequent machining, stamping or other fabricating operations whenever necessary. In the hardened condition the alloys, as those skilled in the art will readily appreciate, are machinable with greater difficulty than in the annealed condition but, if necessary, machining can be performed by the use of carbide type tools.

In the high nickel alloys containing about 90% or more of nickel, we have found it preferable to employ about 4% to 5% aluminum in combination with about 0.25% to 0.75% titanium and angina.

0.5% to 2% silicon. Carbon should be less'than 0.5 %,'preferably from about 0.15% to 0.20%, except that when free machining properties are desired the carbon should preferably be from about 0.2% to 0.3% as indicated hereinbefore. Small amounts of manganese, iron, sulfur, copper, etc'., may be present. The following alloy is typical of the preferred high nickel alloys:

Age Harened g Properti R ol lgd Hard l gfi i i li at soo r.

Proportional L 34, 500 110, 000 118, 000 Proof Stress, p 37, 000 122, 000 134, 000 Yleldstrengtli, p s 1 47,000 143,000 153,000 Tensilestrength, p S 110, 500' 200, 000 208, 000 Per CentElong. in 2. 49. 5 25.0 21.0 Per Cent Reduction of A 67.0 41. 3' 35. l 41 43 The room temperature properties of the alloy after exposure for 16 months at 800 F. illustrate the remarkable stability and freedom from overaging tendencies which this alloy possesses.

The high nickel alloys of the type illustrated by the data in the preceding schedule may be hot worked over the temperature range of about 1400 F. to about 2450 F., preferably within the range of about 2000 F. to 2300 F.

It will be seen from the foregoing description and the specific examples that we have provided nickel alloys combining optimum response to heat treatment with hot malleability. These alloys may be used for various articles of manufacture including rollers and bearing balls, bearing and races therefor, roller chains, drop forgings and tie rods for airplane construction, valve seats and other valve parts, pump rods and the like, pump rod sleeves, pump pistons for high pressures and temperatures, plungers, turbine blades, turbine diaphragm blading, lock washers, screws and nuts, tools, cutting blades and the like, pins and needles, springs and other resilient elements, airplane instrument parts, nozzles for burners, rods, sheets, strip, wire, bars, rolled shapes, etc.

Although the present invention has been described in conjunction with preferred embodiments, it is understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand.

We claim:

1. An alloy containing at least nickel, 0.15% to 0.2% carbon, 4% to 5% aluminum, 0.25% to 0.75% titanium, and 0.5% to 2% silicon, the amounts of aluminum, titanium and silicon within said ranges being such that the ratio of the nickel content to the sum of the content of aluminum, silicon and 2.3 times the titanium is between 11 and 20.

2. An alloy containing 0.15% to 0.2% carbon,

4% to 5% aluminum, up to 2% silicon, the

7 aluminum, 0.25% to 0.75% titanium, up to 2% silicon, and the balance essentially nickel plus small amounts of incidental elements, the amounts of aluminum, titanium and silicon within said ranges being such that the ratio of thenickel content to the sum of the content of aluminum, silicon and 2.3 times the titanium is between 11 and 20.

3. An alloy containing 0.2% to 0.3% carbon, 0.25% to 0.75% titanium, balance being essentially nickel which constitutes at least 90% of the alloy, the amounts of aluminum, titanium and. silicon within said ranges being such that the ratio of the nickel content to the sum of the content of aluminum, silicon and 2.3 times the titanium is between 11 and 20, said alloy having carbon present in the form of graphite which imparts improved machinability.

4. An alloy containing at least 90% nickel, 0.15% to 0.2% carbon, 0.25% to 5% aluminum,

at least 0.25% and under 1% titanium, 0.25% to I 5% silicon, and the balance iron and incidental elements, the amounts of aluminum, titanium and silicon within said ranges being such that 1 the ratio of the nickel content to the sum of the content of aluminum, silicon and 2.3 times the titanium is between 11 and 20.

5. An alloy containing at least 90% nickel, 0.2% to 0.3% carbon, to 0.75% titanium, up to 2% silicon, and the balance iron and incidental elements, the amounts of aluminum, titanium and silicon within said ranges being such that the ratio of the nickel 4% to 5% aluminum, 0.25% 30 REFERENCES CITED The following'references are of record in the file of this patent: 1

v V UNITED STATES PATENTS Number Name Date 1,258,227 Kelley Mar. 5, 1918 1,277,046 Cooper Aug. 27, 1918 1,350,359 Cooper Aug. 24, 1920 1,439,865 Cammen Dec. 26, 1922 1,556,953 Parr Oct. 13,1925 1,572,744 Mercia Feb. 9, 1926 1,587,992 Spitzley June 8, 1926 1,610,262 Cooper Dec. 14, 1926 1,623,948 Fuller Apr. 5, 1927 1,675,798 Franks et a1. July 3, 1928 1,684,131 Franks et a1 Sept. 11, 1928 2,005,433 Lehr June 18, 1935 2,048,165 Pilling July 21, 1936 2,246,078 Rohn June 17, 1941 OTHER REFERENCES Campbell: A List of Alloys, 1930, published by Amer. Soc. for Testing Materials, Philadelphia, Pa., page 26. 

1. AN ALLOY CONTAINING AT LEAST 90% NICKEL, 0.15% TO 0.2% CARBON, 4% TO 5% ALUMINUM, 0.25% TO 0.75% TITANIUM, AND 0.5% TO 2% SILICON, THE AMOUNTS OF ALUMINUM, TITANIUM AND SILICON WITHIN SAID RANGES BEING SUCH THAT THE RATIO OF THE NICKEL CONTENT TO THE SUM OF THE CONTENT OF ALUMINUM, SILICON AND 2.3 TIMES THE TITANIUM IS BETWEEN 11 AND
 20. 